1. Field of the Invention
The present invention relates to methods for displaying graphs illustrating a trace of data samples with respect to coordinate axes and, particularly, to displaying markers on the graphs identifying data samples having a particular value along the trace.
2. Description of Related Art
Electronic system analyzers such as the WILTRON 360 Network Analyzer manufactured by Wiltron Company, 490 Jarvis Drive, Morgan Hill, Calif., are used by system designers and trouble-shooters to measure characteristics of subject systems. Measured characteristics can be compared with expected characteristics to identify problems in subject systems. Often, the measured system characteristics can best be presented to the operator of the system analyzer in graph form. For instance, in the WILTRON 360, which is used with microwave frequency electronic networks, provides the user with the option to display the measured information about transmission and reflection characteristics of the networks in a variety of graphical forms, such as rectilinear phase versus frequency and magnitude versus frequency graphs, or in polar or Smith chart formats.
Often it is useful for an operator to display markers along a trace on a graph identifying samples of interest. As the operator changes scales on the graph or form of graph, the markers are automatically positioned in the proper location so that the operator can keep track of the samples of interest. When a large number of markers appears on a graph or the markers begin to crowd the edges of the field of the graph on the display, information provided by the crowded markers may be lost because of overwriting of the marker symbols. Accordingly, there is a need for an algorithm for displaying markers that overcomes the problems of crowded displays.